Kathe



aienied cian. i?, i195@ HCE THERMGSTATICLHY @NTRLLED SFE- 'EY PMAM?BURNER AND lS'CH DEVKCE F915@ BURNER SYSTEMS to improvements in aprovide the above described combination wherein the hood is of channelform adapted to protect the dame, and special means is provided forcontrolling the heating of the hood by the pilot :dame when the latteris relatively low.

My invention also contemplates the construction of the hood andoperating arm of material having substantially similar coemcients ofexpansion and of approximately equal length so that they aresubstantially equally affected by changes in ambient temperature.

My invention also contemplates the com-bination of the precedingparagraph wherein the control member is an electrical switch of the typeoperable upon movement of the order of a few thousandths of an inch andwherein the switch and the fixed end of the hood have a common mountingmeans whereby a very ne control is obtained, as will be later described.

Other objects and advantages of my invention will be apparent from theaccompanying drawings and description, and the essential featuresthereof will be set forth in the appended claims.

In the drawings,

Fig. 1 is a. side elevational view of one embodiment 'ofmy device, partsbeing broken away to more clearly show the construction;

Fig. 2 is a. bottom plan view of the same:

Figs. 3 and 4 are sectional views taken along similarly numbered linesof Fig. 1; while Fig. 5 is a diagrammatic view showing schematically oneuse of my device in a fuel control system.

Without in any way limiting myself to the speciflc form shown in thevarious views, I have disclosed a main burner I0 and pilot means II forlighting the same which is connected at I2 with a source of combustiblefuel. The pilot is mounted in a block I3 which is rigidly secured in oneend of the hood I4 which is of elongated channel form having an upperweb Ila and down-turned iianges Ilflb so that the pilot name isprotected against accidental extinguishing by being blown out and thepilot dame is directed to burner i0. The right-hand end of the hood it,as viewed in Figs. l and 2, is nxed to bracket means it. The lefthandend is free and positioned adjacent the burner i@ so that the pilot dameissuing from the left-hand end of the hood lights the fuel issuing fromthe burner. The channel ifi is of a material adapted to contract andexpand under the in uence of the pilot flame for e, thermostatic controlpurpose, as will presently appear. Rigidly secured to the free end ofthe hood It is an operating arm i6. The securing means here showncomprises a V-shape band I'I welded or otherwise secured to the hood I4and the arm I6. The free end of the arm I6, moving unrestrained in theopening ita of the bracket I5, is adapted to engage the operator I8 ofan electrical switch I9 which is preferably mounted in the bracket I5.Obviously, any control device, either mechanical or electrical, might beso positioned to be engageable by the arm I6 to provide a control eiectupon expansion and contraction of the hood I4. For the purpose ofproviding a very fine control, where necessary, I have shown a switch I9of the ty-pe adapted to be operated by movement of the member i8 a verysmall amount of the order of a few thousandths of an inch or less. Sucha switch is shown in Patent No. 1,960,020 granted May 22, 1934 to P. K.McGall, but I do not Vdesireto be limited as to the actual switch used.

Obviously, various devices may be provided to 'prevent damage to thecontrol member I9 upon over-travel of the arm I6. The specific meanshere shown comprises a plunger 20 held outwardly from arm IS by means ofa relatively stiff spring 2I housed in the arm. The projection 2| actsas a part of arm I6 until the operator Il can move no farther, afterwhich, spring 2| may Y lbe slightly compressed.l `"=This provision vforovertravel is not essential tothe operationof my invention, butsome suchprovision is generally desirable.

Various means may be provided for controlling the adjustment of theplunger 20 with respect to the operator I8. I have here shown anadjustment Iwhich comprises the mounting of the member IBa on the arm I6by a threaded connection, together with a lock nut 22 so that theeffective length of arm IB may be adjusted as desired. My invention isnot limited to any specific form for providing the adjustment of thespace between members 20 and I8.

One manner of using my invention is shown schematically in Fig. wherevalve 2l controls the ow of fuel'through line 24 to burner I0. Thisvalve is normally closed by spring 25 and is moved to open position -bythe solenoid 28 when the same is energized from the electrical sourceLI,L2. The switch I 8 is of the normally closed type and is openedwhenever the operator I8 is depressed. Obviously, whenever switch I9 lsin its normally closed position depression of the button 21 will closethe electrical circuit so as to open valve 23 to supply fuel to theburner Iii.

In operation, when the hood I4 is cold, it is contracted in length andthe operating arm Iii holds the member I8 depressed so that the switchI9 is open. In this position of the parts, the burner I0 cannot besupplied with fuel as there .is no pilot name to light it. When thepilot II is lit, the flame travels along the hood I4 issuing adjacentthe burner I0 and the hood I4 is heated; causing it to expand. Thisdraws the arm I6 toward the left, as viewed in Fig. 1, so that theplunger 2U finally releases the operator I8. whereupon switch I9 attainsits normally closed position, whereupon the operator may press thebutton 21 so as to energize solenoid 26 causing opening of valve 23 andthe supply of fuel through line 24 to the burner I0 where the fuel isignited by the flame issuing from the hood I6.

It will be noted that the operating arm I6 is below the hood I4 in aposition where it receives very little heat from the pilot ame.

A satisfactory device is provided where the hood I4 is of material whichexpands and contracts under the inuence of the pilot flame while theoperating arm I6 is of material whose length is relatively unaffected byheat, such as Inval'.

There are special cases where a very fine adjustment is desired betweenthe members 20 and I8 and this is particularly difficult where thesafety pilot device is subject to ambient temperatures which varywidely. In such cases, I find it advisable to make the hood I 4 and thearm I8 of materials of substantially the same coeiicient of expansion.For instance, I have made them both of stainless steel with very goodresults. Utilizing this construction, if the ambient temperature shouldincrease considerably, the hood I4 will expand and, since the right-handend is xed, as viewed in Fig. 1, the left-hand end will move toward theleft carrying the band I1 and the end of arm I6 in the same direction.However, the arm I6 being of substantially the'same length as the hoodI4, and parallel thereto, will expand a substantially equal amount sothat the end of the plunger 2|) will remain in substantially the sameabsolute position relative to the switch operator I8. When the switchandthe hood I4 are fastened to the same rigid body, as for instance thebracket I5, this setting may be held within extremely narrow limits. Itwill thus be seen that using this construction and using a micro-switchat I9, I have provided a control which is much finer than others knownto me.

An improvement which may be used to obtain a still finer control isillustrated in Fig. 1, where the hole I4c is provided in the upper wallI4a of the channel-shaped hood, whereby an escapement of hot gases willprovide a greater heat loss, thus producing a contraction of the channelI4 sufficient to shut off gas supply to burner I0 at gas pressures ashigh as one and eight-tenths inches of water pressure.

My safety pilot, however, provides an ignitable flame from the open endof channel I4 at extremely low gas pressures, even after the channel hascontracted to a point where gas can not be supplied to burner III. 'Ihisdevice will provide suiilclent flame to ignite burner I0 at pressures aslow as two-tenths of one inch water pressure. In other words, my devicecan be set to prevent gas supply to burner I!) when gas pressure dropsbelow 1.8 inches water gage although the pilot name is still availableat the open end of channel It until gas pressure drops below 0.2 inchwater gage. This provides a wide margin of safety.

What I claim is:

1. Safety pilot construction comprising an elongated generallyhorizontal hood having xed and free ends, pilot means communicating withone end thereof for heating said hood, an elongated operating armgenerally parallel to said hood and having one end fixed to the free endof said hood, said arm being relatively unaffected by the heat of saidpilot means, said arm and said hood being substantially straight in bothheated and cooled condition, a control member adjacent the other end ofsaid arm and adapted to be operated thereby responsive to elongation andcontraction of said hood under influence of said pilot means, and saidhood and arm having closely similar coeiilcients of expansion and beingof approximately equal length whereby they vary similarly in lengthresponsive to ambient temperatures.

2. Safety pilot construction comprising an elongated generallyhorizontal hood having flxed and free ends, pilot means communicatingwith one end thereof for heating said hood, an elongated operating armgenerally parallel to said hood and having-one end fixed to the free endof said hood, said arm being relatively unaifected by the heat of saidpilot means, said arm and said hood being substantially straight in bothheated and cooled condition, an electrical switch adjacent the other endof said arm and adapted to be operated by contraction of said hood whensaid pilot means is not heating.

3. Safety pilot construction comprising an elongated generallyhorizontal hood having iixed and free ends, pilot means communicatingwith one end thereof for heating said hood, an elongated operating armgenerally parallel to said hood and having one end xed to the free endof said hood, said arm being relatively unaffected by the heat of saidpilot means, said -arm and said hood being substantially straight inboth heated and cooled condition, an electrical switch adjacent theother end of said arm and adapted to be operated by contraction of saidhood when said pilot means is heating at a low rate.

4. Safety pilot construction comprising an elongated generallyhorizontal channel, said channel being of material expansible whenheated, said channel having one end fixed and the other end free, a mainburner adjacent the free end of said channel, pilot means providing aname within said channel adapted to travel from the xed end toward thefree end thereof, an elongated operating arm generally parallel to saidchannel and having one end xed to the free end of said channel, said armand said channel being substantially straight in both heated and cooledcondition, and a control member adjacent the other end of said arm andadapted to be operated thereby responsive to elongation and contractionof said channel under influence of said ame, whereby 'said channelprotects said flame from being extinguished while acting as athermostatic control member and said channel provides means forconducting said pilot ilame to said main burner.

5. The combination of claim 4 wherein a hole is provided through the topwall of said channel intermediate its ends in position to pass a portionof the heat of said pilot flame through the top wall of said channel,whereby to reduce the heating effect of a flame upon said channel sothat the latter will contract and operate said control member whilepilot flame is s'till available adjacent said main burner.

6. Safety pilot construction comprising an elongated generallyhorizontal hood having xed and free ends. pilot means communicating withone end thereof for heating said hood, an elongated operating armgenerally parallel to said hood and having one end fixed to the free endof said hood, said arm being relatively unaffected by the heat of saidpilot means, said arm and said hood being substantially straight in bothheated and cooled condition, an electrical switch operable by movementof the order of a few thousandths of an inch and having an operatoradjacent the other end of said arm adapted to be operated by l5 UNITEDSTATES PATENTS Number Name Date 1,886,876 Gauger Nov. 8, 1932 1,963,957Cunningham June 26, 1934 m 2,269,356 Beam et al Jan. 6, 1942 y 2,392,065Rodgers Jan. 1, 1946 LEO KATHE.

REFERENCES CITED The following references are of record in the file ofthis patent:

